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package javax.crypto.spec;

import java.security.spec.AlgorithmParameterSpec;


This class specifies the parameters used with the
RC5
algorithm.

 The parameters consist of a version number, a rounds count, a word
size, and optionally an initialization vector (IV) (only in feedback mode).

 This class can be used to initialize a Cipher object that implements the RC5 algorithm as supplied by
RSA Security LLC,
or any parties authorized by RSA Security.

Author:Jan Luehe
Since:1.4
/**
 * This class specifies the parameters used with the
 * <a href="http://tools.ietf.org/html/rfc2040"><i>RC5</i></a>
 * algorithm.
 *
 * <p> The parameters consist of a version number, a rounds count, a word
 * size, and optionally an initialization vector (IV) (only in feedback mode).
 *
 * <p> This class can be used to initialize a {@code Cipher} object that
 * implements the <i>RC5</i> algorithm as supplied by
 * <a href="http://www.rsa.com">RSA Security LLC</a>,
 * or any parties authorized by RSA Security.
 *
 * @author Jan Luehe
 *
 * @since 1.4
 */
public class RC5ParameterSpec implements AlgorithmParameterSpec {

    private byte[] iv = null;
    private int version;
    private int rounds;
    private int wordSize; // the word size in bits

    
Constructs a parameter set for RC5 from the given version, number of
rounds and word size (in bits).

Params:
  • version – the version.
  • rounds – the number of rounds.
  • wordSize – the word size in bits.
/**
     * Constructs a parameter set for RC5 from the given version, number of
     * rounds and word size (in bits).
     *
     * @param version the version.
     * @param rounds the number of rounds.
     * @param wordSize the word size in bits.
     */
    public RC5ParameterSpec(int version, int rounds, int wordSize) {
        this.version = version;
        this.rounds = rounds;
        this.wordSize = wordSize;
    }

    
Constructs a parameter set for RC5 from the given version, number of
rounds, word size (in bits), and IV.

 Note that the size of the IV (block size) must be twice the word size. The bytes that constitute the IV are those between iv[0] and iv[2*(wordSize/8)-1] inclusive. 
Params:
  • version – the version.
  • rounds – the number of rounds.
  • wordSize – the word size in bits.
  • iv – the buffer with the IV. The first 2*(wordSize/8) bytes of the buffer are copied to protect against subsequent modification.
Throws:
/**
     * Constructs a parameter set for RC5 from the given version, number of
     * rounds, word size (in bits), and IV.
     *
     * <p> Note that the size of the IV (block size) must be twice the word
     * size. The bytes that constitute the IV are those between
     * {@code iv[0]} and {@code iv[2*(wordSize/8)-1]} inclusive.
     *
     * @param version the version.
     * @param rounds the number of rounds.
     * @param wordSize the word size in bits.
     * @param iv the buffer with the IV. The first {@code 2*(wordSize/8)}
     * bytes of the buffer are copied to protect against subsequent
     * modification.
     * @exception IllegalArgumentException if {@code iv} is
     * {@code null} or {@code (iv.length < 2 * (wordSize / 8))}
     */
    public RC5ParameterSpec(int version, int rounds, int wordSize, byte[] iv) {
        this(version, rounds, wordSize, iv, 0);
    }

    
Constructs a parameter set for RC5 from the given version, number of
rounds, word size (in bits), and IV.

 The IV is taken from iv, starting at offset inclusive. Note that the size of the IV (block size), starting at offset inclusive, must be twice the word size. The bytes that constitute the IV are those between iv[offset] and iv[offset+2*(wordSize/8)-1] inclusive. 
Params:
  • version – the version.
  • rounds – the number of rounds.
  • wordSize – the word size in bits.
  • iv – the buffer with the IV. The first 2*(wordSize/8) bytes of the buffer beginning at offset inclusive are copied to protect against subsequent modification.
  • offset – the offset in iv where the IV starts.
Throws:
/**
     * Constructs a parameter set for RC5 from the given version, number of
     * rounds, word size (in bits), and IV.
     *
     * <p> The IV is taken from {@code iv}, starting at
     * {@code offset} inclusive.
     * Note that the size of the IV (block size), starting at
     * {@code offset} inclusive, must be twice the word size.
     * The bytes that constitute the IV are those between
     * {@code iv[offset]} and {@code iv[offset+2*(wordSize/8)-1]}
     * inclusive.
     *
     * @param version the version.
     * @param rounds the number of rounds.
     * @param wordSize the word size in bits.
     * @param iv the buffer with the IV. The first {@code 2*(wordSize/8)}
     * bytes of the buffer beginning at {@code offset}
     * inclusive are copied to protect against subsequent modification.
     * @param offset the offset in {@code iv} where the IV starts.
     * @exception IllegalArgumentException if {@code iv} is
     * {@code null} or
     * {@code (iv.length - offset < 2 * (wordSize / 8))}
     */
    public RC5ParameterSpec(int version, int rounds, int wordSize,
                            byte[] iv, int offset) {
        this.version = version;
        this.rounds = rounds;
        this.wordSize = wordSize;
        if (iv == null) throw new IllegalArgumentException("IV missing");
        int blockSize = (wordSize / 8) * 2;
        if (iv.length - offset < blockSize) {
            throw new IllegalArgumentException("IV too short");
        }
        this.iv = new byte[blockSize];
        System.arraycopy(iv, offset, this.iv, 0, blockSize);
    }

    
Returns the version.

Returns:the version.
/**
     * Returns the version.
     *
     * @return the version.
     */
    public int getVersion() {
        return this.version;
    }

    
Returns the number of rounds.

Returns:the number of rounds.
/**
     * Returns the number of rounds.
     *
     * @return the number of rounds.
     */
    public int getRounds() {
        return this.rounds;
    }

    
Returns the word size in bits.

Returns:the word size in bits.
/**
     * Returns the word size in bits.
     *
     * @return the word size in bits.
     */
    public int getWordSize() {
        return this.wordSize;
    }

    
Returns the IV or null if this parameter set does not contain an IV.

Returns:the IV or null if this parameter set does not contain an IV.
Returns a new array each time this method is called.
/**
     * Returns the IV or null if this parameter set does not contain an IV.
     *
     * @return the IV or null if this parameter set does not contain an IV.
     * Returns a new array each time this method is called.
     */
    public byte[] getIV() {
        return (iv == null? null:iv.clone());
    }

   
Tests for equality between the specified object and this object. Two RC5ParameterSpec objects are considered equal if their version numbers, number of rounds, word sizes, and IVs are equal. (Two IV references are considered equal if both are null.) 
Params:
  • obj – the object to test for equality with this object.
Returns:true if the objects are considered equal, false if obj is null or otherwise.
/**
     * Tests for equality between the specified object and this
     * object. Two RC5ParameterSpec objects are considered equal if their
     * version numbers, number of rounds, word sizes, and IVs are equal.
     * (Two IV references are considered equal if both are {@code null}.)
     *
     * @param obj the object to test for equality with this object.
     *
     * @return true if the objects are considered equal, false if
     * {@code obj} is null or otherwise.
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof RC5ParameterSpec)) {
            return false;
        }
        RC5ParameterSpec other = (RC5ParameterSpec) obj;

        return ((version == other.version) &&
                (rounds == other.rounds) &&
                (wordSize == other.wordSize) &&
                java.util.Arrays.equals(iv, other.iv));
    }

    
Calculates a hash code value for the object.
Objects that are equal will also have the same hashcode.

/**
     * Calculates a hash code value for the object.
     * Objects that are equal will also have the same hashcode.
     */
    public int hashCode() {
        int retval = 0;
        if (iv != null) {
            for (int i = 1; i < iv.length; i++) {
                retval += iv[i] * i;
            }
        }
        retval += (version + rounds + wordSize);
        return retval;
    }
}